1. Field of the Invention
This invention relates generally to treatment of fluids and more particularly to a device and method for the removal of unwanted materials, such as chlorine, from water.
2. Description of Related Art
Starting after the U.S. Civil War, the recognition and linking of macroscopic and microscopic pathogens to the aesthetic and health qualities of water resulted in the search for effective water disinfection and treatment procedures. Soon thereafter, chlorine was identified as a disinfecting agent. Towards the end of the 19th century, there were several recorded instances of the use of chlorine compounds for the disinfection of water and, with increasing experience, the effectiveness of chlorine treatment of water became more widely recognized and appreciated. The introduction of water chlorination, as a continuous process, occurred soon after the turn of the century. Currently, approximately 80% of all potable water systems in the U.S. contain chlorine as a disinfectant.
It is now known that chlorine passes across cell membranes and chemically bonds to amino acids, creating more complex chloro-compounds, disabling cellular protein synthesis, which in turn effectively destroys a micro-organism.
However, the treatment of water with chlorine is not without its drawbacks. Even in lower concentrations, such as originally used by commercial food processors and bottlers, chlorine creates an objectionable odor and taste. Also, as chlorine is added to water containing pathogenic microorganisms, the highly reactive chlorine combines with fatty acids and carbon fragments to form a variety of toxic compounds.
During the mid 1970's, monitoring efforts began to identify widespread toxic contamination of the water supplies in many parts of the world. In fact, epidemiological studies at the same time began to suggest a link between the ingestion of toxic chemicals in the water and elevated cancer mortality risks, as well as other diseases, such as arteriosclerosis, heart disease, anemia, high blood pressure, allergic reactions, and adverse conditions related to the drying and damaging of hair and skin.
Additional studies since the 70's indicate that chlorine and the compounds it forms in water can also be inhaled and absorbed through the skin by persons during bathing or showering. In fact, according to research presented at a meeting of the American Chemical Society in the 1980's, it was shown that "taking long hot showers is a health risk." In summary, this presentation stated that "taking showers, and to a lesser extent baths, lead to a greater exposure to toxic chemicals contained in water than does drinking the water. Due to the increased temperatures and surface area, the chemicals evaporate out of the hot water and are inhaled. They can also spread through the house and be inhaled by others. Householders can receive 6 to 100 times more of the chemicals by breathing the air around showers and baths than they would by drinking the water."
Different devices and methods for dechlorination of water have been used both at the point-of-entry ("POE") into a commercial, industrial or residential building, and the point-of-use ("POU") at the faucet, shower head or tap.
POE systems typically are in the form of an aerator, or a large organic or inorganic filtering media bed. Although applicable in some instances, these systems have potential problems, and have fallen under close scrutiny, due to the possibility of pathogenic reintroduction back into the water system, after the point of dechlorination. Because of this possibility, and the recent advancement in water treatment technology, POU water treatment systems have become widely accepted and are now primarily used in residential, and to a large degree, in commercial and industrial applications.
Both organic and inorganic filtering media are known for use in dechlorination. Carbon (organic) filtering media are used either alone, or in conjunction with other systems, such as reverse osmosis or distillation, or may be used with inorganic filtering media, such as cation/anion resins.
Carbon filtration comes about through the process of adsorption, which is dependent upon finite attachment sites located on the carbon filtering media, resulting in:
1.) A low volume capacity, typically measured or rated in (X) 100 gallons; and
2.) High temperature intolerance; a decrease in filtering efficiency as temperature increases up to a point where the filtration ceases and a releasing of filtered contamininates occurs (off-loading) back into the water, thereby producing a more contaminated water than if left unfiltered.
Some inorganic filtering media, such as cation/anion resins, have shortcomings similar to those of carbon, in that they have a very low volume capacity and become ineffective at higher temperatures.
Other known inorganic medias use a oxidation-reduction treatment method of the "electronegative cell potential type", based on the Voltaic or Galvanic cell, utilizing electrochemical principals. They are of a type that produce electricity as a result of spontaneous chemical change due to the electronegative potential created by the dissimilar metals used. This type of cell was first used by Alessandro Volta (1745-1827). He was able to generate electric current by stacking pieces of copper and zinc in salted water. The combination of copper and zinc, therefore, recreates the classic model of a chemically reactive cell, with the zinc and copper acting as electrodes. As the water passes through the "cell" the substances suspended in the water have a tendency to either be reduced or oxidized, thereby resulting in the molecular transformation of the substances. By using this type of method, distinct advantages exist. As the filtering media is typically metallic it possesses both a high volume capacity, measured or rated by (X) 1000 gallons, and a high temperature/high efficiency capacity.
One such prior art filter media is disclosed in U.S. Pat. No. 4,642,192, which discloses an "electronegative cell potential type" chlorine filter media, of the type discussed immediately above. The preferred media to filter out chlorine disclosed in this patent is brass (a mixture of copper and zinc). Although this patent mentions the use of zinc to remove chlorine, it points out in column 5, lines 17 through 23 thereof that although zinc is theoretically more spontaneous than copper, because it has a more positive potential, in actual practice it had been found that a zinc and copper alloy, such as brass, is more effective in the removal of dissolved chlorine than is either pure zinc or pure copper or a heterogeneous mixture thereof. Additionally, in lines 24 through 28 of this same column 5, it is recited that brass is also preferred from the viewpoint of chemical safety since it does not have the violent reactivity to aqueous fluids as do metals such as pure sodium, potassium, calcium and zinc. However, applicant's recent studies have demonstrated that the use of zinc alone, produces better results than a cooper/zinc mixture, thus coinciding with traditional inorganic chemistry theories. Also, since zinc is a transition element (copper is not) and not in the same chemical family, it does not have similar chemical properties, including reactivity, as does sodium, potassium (alkali metal elements) and calcium (alkaline earth metal element). It is a well known fact that zinc has an OSHA/MSDS and NFPD reactivity rating of #1. This is defined as: "Materials which in themselves are normally stable, but which can become unstable at elevated temperatures and pressures, or which may react with water with some release of energy, but not violently." In contrast to zinc, sodium, potassium and calcium are all given a reactivity rating of #2. This is defined as: "Materials which in themselves are normally unstable and readily undergo violent chemical change, but do not detonate. Also materials which may react violently with water or which may form potentially explosive mixtures with water. Additionally, this patent fails to take into account recent government studies and regulations, such as those from the Environmental Protection Agency (IIEPAII), which has set the maximum contaminant levels for copper in potable water as 5 times more stringent than for zinc. That is, copper's limit is one part per million (PPM), while zinc is much more tolerated, at 5 PPM.
The following disadvantages also exist with "electronegative cell potential type" filter medias:
1. The classic models either use acids as the fluid medium to activate the reaction, or when using a non-acidic fluid medium, electricity is driven across the cell.
If neither of these is used, the reaction in the cell is dependent on the relatively weak electrical potentials created by the difference of the standard reduction potentials (E.degree.values at 25 degrees C.) of each of the dissimilar materials used (as is the case for the "electronegative cell potential types").
In this connection, the disclosure in U.S. Pat. No. 4,642,192, starting at line 57 of column 4 and ending at line 28 in column 5 is incorporated herein, in its entirety, by this reference thereto. Therefore, for example, the difference in the reduction potentials between copper and zinc would be 1.10 volts, arrived at as follows: ##STR1## When using this method to oxidize chlorine, zinc will react more spontaneously than the copper. The copper will actually impede the reaction between zinc and chlorine, acting as an electronic buffer between the zinc and the chlorine, as follows: ##STR2##
Therefore, as shown, when 100% zinc combines with chlorine the reaction will be 3 times more spontaneous than a reaction of 100% copper with chlorine, and 1.5 times as spontaneous as the combination of a 50/50 mixture of copper and zinc with chlorine.
2. The "electronegative cell potential types" that use copper are further at risk of introducing copper into water, and exceeding the above EPA regulations for copper content in potable water.
Other prior art devices to remove chlorine from water supplies are known. These devices generally include filtering means for attachment in or to a waterline in a commercial, industrial, or residential setting, or to replace a faucet or shower head therein. By-pass means may be added to such devices, and valves may be switched or changed if it is desired to allow unfiltered water to exit from or travel around the filter means. In addition, as discussed above, different methods are used, and differing filtering media are held in these known devices to selectively remove, specific unwanted particles or materials from the water passing therethrough.
One type of filtering device now available for removing chlorine from water is disclosed in applicant's copending application, referred to above. The device disclosed therein is a compact filter assembly having a recessed inlet connected to the end of a waterline in a shower. The assembly contains a filtering media to filter out unwanted chlorine in the water passing through the filter and an adjacent internal baffle means to direct the flow of water more evenly through the filtering media. This filter assembly also includes internal placement and reinforcing means to properly locate the internal baffle means and to strengthen the two parts of the filter housing. A water shut-off means and a compact shower head may also be added after the filter media, and does not greatly increase the size of this compact filter means.
U.S. Pat. No. 2,582,388, discloses another prior art water filter, for insertion into a waterline, having two parts threaded together to form a shell or housing, having a plurality of screens held in an inlet to and outlet from the interior thereof. Layers of activated charcoal, separated by a layer of silica and screens are arranged in the shell to filter water passing through the shell.
U.S. Pat. No. 3,760,951, incorporates U.S. Pat. No. 2,582,388 therein by reference, and discloses a similar water filter for insertion into a waterline by means of quick-disconnect bayonet fittings that allow the filter to be easily removed for cleaning or replacement.
U.S. Pat. No. 3,780,869, discloses a water filter, for insertion into a waterline, having a plurality of compartments with multiple filtering elements of sheep's wool therein. The filter includes two separate body parts which are held together by threaded portions that allow the body to be taken apart and put back together to replace or clean the multiple filter elements contained therein. The filter also includes a valve for shifting between filter and non-filter positions.
U.S. Pat. No. 3,822,018, discloses a water filter, for insertion into a waterline, having two hemispherical sections joined together by threaded portions. The filter has a plurality of cylindrical filter elements annularly arranged therein containing natural wool, charcoal, cork and the like, and includes a valve for directing water through the filter elements or for directing water through the device, unfiltered.
U.S. Pat. No. 4,107,046, discloses a filter cartridge for an internally by-passable water purifier apparatus. The apparatus includes valve means for directing water through the filter cartridge, which contains granulated carbon mixed with a silver zeolite, and may be sandwiched between fibrous sheets of material, such as felt, before it exits the apparatus, and another valve means for directing water to the outlet of the apparatus along a path that by-passes the filter cartridge.
U.S. Pat. No. 4,172,796, discloses a water faucet having a water purification or filtering means, made from activated carbon, or carbon with oligodynamic silver, formed therein. Valve means are provided for selecting the flow of water therethrough to either discharge filtered or unfiltered water.
U.S. Pat. No. 4,504,389, discloses a water faucet having a separate housing containing a removable cartridge or filter element made from various stages of polyethylene and activated carbon particles therein, and valve means for selecting whether the faucet provides filtered or unfiltered water. The filter cartridge is replaceable by removing a cap covering the separate housing holding the cartridge, lifting out the old cartridge, and inserting a new cartridge.
U.S. Pat. No. 5,008,011, discloses a shower dechlorinator fabricated in the form of a short cylindrical filter housing having two separate end caps with inlet and outlet means for attachment between the outlet pipe for a shower and a shower head. The filter housing is filled with granulated or randomly oriented fibrous material in the form of a copper/zinc metal alloy. This patent is limited in its disclosure to the specific shape of the filter housing and the copper/zinc metal alloy filter media described therein. The shape and size of the filter housing is akin to that of a so-called "pipe bomb", and the copper/zinc metal alloy is similar, if not identical, to that disclosed in U.S. Pat. No. 4,642,192 discussed above, and suffers from the same problems discussed in connection with this patent.
While the foregoing prior art devices, filter media and methods provide improved filtration of water passing through them, they are not adapted to meet the health and safety standards of today, nor do they meet the requirements, such as in baths or showers, that larger volumes of heated water having increased amounts of unwanted chlorine therein be safely filtered out. Furthermore, while the above-mentioned prior art provide some limited improvements in the filtering art, there remains the need in the art for a filter assembly that provides maximum strength, as well as the most efficient method of filtering out unwanted materials, such as chlorine, while at the same time meeting the more stringent health and safety regulations of local communities and such governmental agencies as the EPA.